Product contamination can result from both raw materials and incorrect food production, handling and storage procedures. In particular, it can be found in raw (or not well pasteurized) milk, soft and blue cheeses (eg brie, gorgonzola and camembert), ice cream, raw or undercooked meats (eg pâté, salami, sausages, hamburgers and frankfurters), raw or smoked fish, vegetables and ready-to-eat foods without cooking (already washed salads, pre-cut fruit, meat-based rotisserie products).
Listeria can also multiply in frozen foods, therefore it is important to maintain an adequate cold chain in the case of buying packaged products. It should however be specified that the onset of the disease is conditioned by the individual's susceptibility and the number of bacteria present in the food at the time of ingestion.
